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Trade Names Can Confuse Sight Glass Selection
By: Jeff Watkins, New Brunswick Scientific
Most engineers know that Pyrex is a trademark of Corning Glass, representing their line of borosilicate glass products. Few, however, know that an early form of borosilicate glass was called Duran Glass when it was introduced in Europe in 1893. Today, one can find borosilicate glass products identified as such by well known industry suppliers but there are also trade names in use. There is, for instance, a line of borosilicate street light lenses called Endural offered by Holophane and a line of borosilicate laboratory glassware from Bejing Glass Works called Bomex. In each case these products are also identified as a borosilicate formulation and they meet industry standards.
These are legitimate grounds for the use of trade names. The procedure for manufacturing borosilicate glass is not a trade secret but it is somewhat involved so the characteristics of glass produced by this procedure can vary. For that reason producers in some market sectors have compelling commercial reasons for offering their products under a distinctive trade name, assuring users of the integrity and quality of their products. But they are also quick to identify their products as borosilicate glass.
Common glass, the soda-lime variety, has been around for centuries, of course, dating back to ancient Egypt. It is an amorphous solid generally produced by heating a mixture of the oxides of silicon, calcium and sodium. This formulation accounts for some 90% of all glass produced today. Borosilicate glass is similar but it is produced by substituting boric oxide for some of the silicon oxide. The result is a glass that has significantly better resistance to thermal shock and chemical corrosion as well as higher application temperature. Some sources report that borosilicate glass must contain a minimum of 5% boron but the more commonly accepted standard, as published in the McGraw-Hill Glass Engineering Handbook (McGraw-Hill, 1984) requires a minimum of 12% boron.
Unfortunately, because borosilicate glass is expensive and rather difficult to produce, glass products of lesser qualities may be marketed for demanding industrial applications under a trade name that conceals the fact that they are, essentially, common soda-lime formulations.
A case in point arose recently when a US manufacturer began offering sight glasses for critical chemical and pharmaceutical applications under a trade name that strongly suggested that it was borosilicate glass. A sample of that glass was subjected to quantitative analysis in an independent testing laboratory. Surprisingly, while the manufacturer specified that the glass contained “up to 5%” boron, the test revealed that it contained none at all. In fact the tests revealed that the sample was plain soda lime and further that it would be rated “Non –Parenteral” the lowest grade of glass defined by US Pharmacopoeia Standards.
In the final analysis, then, it is up to the working engineer’s due diligence to ensure that what goes into critical service requiring the characteristics of borosilicate glass is, in fact, truly borosilicate glass. In the case of sight glass trade names, the answer to the classic question, “what’s in a name?”, is the integrity of an entire processing system and the safety of its operators.
By: Jeff Watkins, New Brunswick Scientific
Most engineers know that Pyrex is a trademark of Corning Glass, representing their line of borosilicate glass products. Few, however, know that an early form of borosilicate glass was called Duran Glass when it was introduced in Europe in 1893. Today, one can find borosilicate glass products identified as such by well known industry suppliers but there are also trade names in use. There is, for instance, a line of borosilicate street light lenses called Endural offered by Holophane and a line of borosilicate laboratory glassware from Bejing Glass Works called Bomex. In each case these products are also identified as a borosilicate formulation and they meet industry standards.
These are legitimate grounds for the use of trade names. The procedure for manufacturing borosilicate glass is not a trade secret but it is somewhat involved so the characteristics of glass produced by this procedure can vary. For that reason producers in some market sectors have compelling commercial reasons for offering their products under a distinctive trade name, assuring users of the integrity and quality of their products. But they are also quick to identify their products as borosilicate glass.
Common glass, the soda-lime variety, has been around for centuries, of course, dating back to ancient Egypt. It is an amorphous solid generally produced by heating a mixture of the oxides of silicon, calcium and sodium. This formulation accounts for some 90% of all glass produced today. Borosilicate glass is similar but it is produced by substituting boric oxide for some of the silicon oxide. The result is a glass that has significantly better resistance to thermal shock and chemical corrosion as well as higher application temperature. Some sources report that borosilicate glass must contain a minimum of 5% boron but the more commonly accepted standard, as published in the McGraw-Hill Glass Engineering Handbook (McGraw-Hill, 1984) requires a minimum of 12% boron.
Unfortunately, because borosilicate glass is expensive and rather difficult to produce, glass products of lesser qualities may be marketed for demanding industrial applications under a trade name that conceals the fact that they are, essentially, common soda-lime formulations.
A case in point arose recently when a US manufacturer began offering sight glasses for critical chemical and pharmaceutical applications under a trade name that strongly suggested that it was borosilicate glass. A sample of that glass was subjected to quantitative analysis in an independent testing laboratory. Surprisingly, while the manufacturer specified that the glass contained “up to 5%” boron, the test revealed that it contained none at all. In fact the tests revealed that the sample was plain soda lime and further that it would be rated “Non –Parenteral” the lowest grade of glass defined by US Pharmacopoeia Standards.
In the final analysis, then, it is up to the working engineer’s due diligence to ensure that what goes into critical service requiring the characteristics of borosilicate glass is, in fact, truly borosilicate glass. In the case of sight glass trade names, the answer to the classic question, “what’s in a name?”, is the integrity of an entire processing system and the safety of its operators.
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